Infectious Diseases A-Z: Avian influenza outbreaks

March 13, 2017

North American outbreaks of avian influenza A(H7N9) — often referred to as "bird flu" — have public health officials paying close attention. The Centers for Disease and Prevention (CDC) says the risk to the public's health from the H7N9 virus outbreak in commercial poultry in the U.S. is low. The U.S. Department of Agriculture says this is not the same virus that has affected poultry and infected humans in Asia. In China, there have been recent confirmed cases of human infections of A(H7N9) virus. Human infections with avian influenza A(H7N9) virus were first reported in China in 2013.

Mayo Clinic infectious diseases specialist Dr. Pritish Tosh says, "When we’re talking about avian influenza cases affecting humans, it is in people who have had close contact with poultry or other types of birds that could carry or get infected with avian influenza. Often in these outbreaks, you will see a handful of cases of people who have had no contact with a sick bird as part of the outbreak but instead got it from somebody else who got it from a sick bird."

Dr. Tosh adds, "When we start to see really highly efficient transmission between people, human-to-human transmission of a novel strain, that's when we get really concerned that this could be the next pandemic strain."

Most avian influenza is spread worldwide by migratory waterfowl which then can pass it along to poultry. In humans, influenza is a respiratory illness. In birds, it is a gastrointestinal illness. Dr. Tosh says, "Avian influenza viruses infecting humans are similar in many ways to human influenza viruses infecting humans. It's often spread through respiratory droplets or other respiratory kinds of secretions from person- to- person. Often, the person who’s getting it from a sick bird is getting it through their droppings. But when it’s spread from person- to- person, it’s through their respiratory secretions — usually through droplets."

The CDC offers these tips to prevent exposure:

Avoid wild birds, or observe them only from a distance.

Avoid contact with poultry that appear ill or have died.

Avoid contact with surfaces that appear to be contaminated with feces from wild or domestic birds.

"It’s important that if somebody were to go near poultry, whether in the U.S. or elsewhere in the world, and develop some sort of respiratory infection, that they let his or her health care provider know," says Dr. Tosh.